Fluidic oscillators for delivering a fan spray of windshield washer liquid upon a vehicle glass or windshield are well known in the art and embodied in such patents as U.S. Pat. Nos. 4,157,161, 4,185,777, 4,463,904, 4,508,267 and 4,645,126, all assigned to the assignee hereof, and incorporated herein by reference. These patents relate to fluidic oscillator systems for cyclically deflecting a liquid jet between positions defined by a pair of end walls. Iterations in vehicle design can affect the product design cycle time.
The object of the present invention is to provide a novel fluidic oscillator and method which reduces product design cycle time by allowing easier creation of various iterations of the fluidic oscillator design, as opposed to the novel design control through the "critical orifice" approach. Critical orifices being very sensitive areas, iterations require precision machining in contrast in changing the width of passages in the invention proposed herewith.
A further object of the invention is to provide a system which allows the fine-tuning of the performance of a fluidic oscillator after the fabrication of the injection molding tool which further compresses the design cycle time and can prevent actually having to rebuild the molding tool in some instances.
Still a further object of the invention is to provide a fluidic oscillator circuit with aspect ratios closer to 1.0. This is advantageous for droplet size control which is an important feature for windshield washers.
Still a further object of the invention is to provide a method in which the size of the fluidic circuit and consequently the whole assembly can be reduced, making it more attractive for packaging, styling and material saving. This aspect also requires smaller tools and, therefore, small presses which further enhances the idea for reduction in total system cost.
Finally, a further object of the invention is to provide independent controls for two sets of slots or passages to allow fine-tuning of spray output during application, where different spray angles and different flow rates are needed based on varying working environment.
According to the invention, a conventional fluidic oscillator silhouette or circuit of the type disclosed, for example, in Bray U.S. Pat. No. 4,645,126 or Stouffer U.S. Pat. No. 4,508,267, in which a power nozzle is coupled to a source of liquid under pressure, feeds an oscillation chamber having an upstream end and a downstream end. A pair of opposed control ports at the upstream end of the chamber is coupled by a pair of control passages to control passage egresses the downstream end of the oscillation chamber. According to the invention, at least one power nozzle bypass passage, and preferably two, connect the control passages with the source of liquid under pressure. This results in a more advantageous windshield washer because it provides more flow from a smaller unit. By adjusting the sizes of the bypass passages, fine-tuning of the spray output for each application can be achieved where different spray angles and different flow rates are needed based on the varying working environment. Moreover, this permits the size of the fluidic circuit, and consequently the whole assembly, to be reduced, making it far more attractive in packaging and styling and material saving. It also requires small tools and therefore smaller presses which further enhances the concept of reduction for total system cost. Moreover, the fluidic circuit can have aspect ratios closer to 1.0 which allows better droplet size control which is an important feature for windshield washers.